I use RocTek for cut/fil calculations, but the program is old and basic, I'm trying to transition to Civil 3D 2012 right now. Typically I create "no work zones" around my building footprints, so that I can do a more detailed take-off in those areas for over-excavations and that sort of thing. Right now I'm using Civil 3D to create an existing surface, a proposed surface, and then a volume from between the two. I thought if I just traced my proposed contours over the existing within the building footprint that I would get what I was looking for. However, analysis of the cut/fill volume shows that there are still some changes being made around the edges of the building.
Is there a specific way to make a proposed surface, but leave parts of the existing surface untouched?
See attached photo. The upper middle portion of the screen is where the building is (forgot to turn on layer). You can kind of see how I've run the proposed contours over the existing, however there's still cut areas within the building footprint.
There are different boundary types. Outer, Show, Hide and Data clip along with using destructive and non destructive break lines. If you search for Boundaries in the help they explain them all. To add to the menu, you can look into masks. This should give you the info you need to do what you need to.